Petroleum distillate fuels



United States Patent PETROLEUM DISTILLATE FUELS John V. Clarke, Jr.,Cranford, and Stephen J. Metro,

Scotch Plains, N.J., and John O. Smith, Jr., Swampscott, Mass, assignorsto Esso Research and Engineering Company, a corporation of Delaware NoDrawing. Application October 30, 1957 Serial No. 693,246

7 Claims. (21. 44-72 The present invention relates to improvedhydrocarbon oil compositions and more particularly relates to improvedpetroleum distillate fuels boiling in the range be tween about 75 F. andabout 750 F. having incorporated therein a new class of additivematerials which markedly improve the stability of such fuels, reducerusting and corrosion of metallic surfaces with which the fuels comeinto contact in the presence of water, and greatly alleviate theexplosive hazards involved in handling such fuels.

Instability due to the presence of unsaturated hydrocarbons and otherrelatively reactive materials in petroleum distillate fuels boilingbetween about 75 F. and about 750 F. constitutes a serious problem inconnection the use and handling of such fuels. The unstable constituentsof the fuels gradually oxidize or otherwise react during storage to forminsoluble sludge and sediment which are often responsible for thesubsequent clogging .of fuel lines, filters and orifices in engines and,burner systems in which the fuels are used. Such clogging usuallynecessitates the shutting down and cleaning of the fuel and corrosion ofmetals in the presence of moisture is considered a serious deficiency inpetroleum distillate fuels. Such fuels are normally stored in tanksequipped with breather devices to take care of expansion and contractiondueto temperature fluctuations. Moisture from the air which enters thetank condenses on the tank walls and results in theformation of a highlycorrosive aqueous phase which. quickly nus-ts out tank bottoms. Smallamounts of waterentrained in fuel from such-tanks may cause the rustingand corrosion offuel lines, engines, nozclass of additive materialswhich, when incorporated in r petroleum distillate fuels, overcome thedifficulties enumerated above. It has been found that the additivematerials'of the invention effectively stabilize petroleum distillatefuels and prevent the oxidation of unstable fuel constituents; reducethe rusting and corrosion of wet or 2,904,416 Patented Sept. 15, 1959damp metallic surfaces with which the fuels come into contact; andincrease the electrical conductivity of the fuels, thus permittingstatic electricity to dissipate rapidly and reducing the explosivehazards involved in handling such fuels. Heretofore it has beennecessary to incorporate separate additives in such fuels in order toovercome these deficiencies. The additives of this invention not onlyobviate the necessity for the use of multiple additives but in additionare considerably more effective than many of the additive materialheretofore used.

The additive materials which are incorporated into the fuels of thepresent invention are tetra alkyl ammonium salts of alkylpolyalkyleneoxy esters of phosphoric acid and have the general formulawhere R is an alkyl group containing from 2 to 13 carbon atoms, R is adivalent aliphatic hydrocarbon radical having from 2 to 8 carbon atoms,n is from 8 to 18, x is 1 or 2, and R" is an-alkyl group containing from1 to 4 carbon atoms. Specific examples of such compounds include thetetra methyl ammonium salt of ethyl pentapr'opoxy phosphate, the tetraethyl ammonium salt of propyl octaethoxy phosphate, the tetra ethylammonium 'salt of butyl dodecapropoxy phosphate, the tetra prop ylammonium salt of pentyl decapropoxy phosphate, and the tetra butylammonium salt of dodecyl hexadecabutoxy phosphoric acid. The tetra ethylammonium salts of the alkyl polypropoxy phosphates are preferred forpurposes of the present invention and the tetra ethyl ammonium salt ofn-butyl dodecapropoxy phosphate is particularly preferred.

The alkyl polyalkyleneoxy esters of phosphoric acid from which the ionicadditives of the present invention are prepared are the reactionproducts of monoethers of polyalkylene glycols -'with P 0 Thesemonoethers are well known articles of commerce and are prepared bycondensing an alkylene oxide such as ethylene oxide, propylene oxide ormixtures of the two, with an aliphatic compound containing a hydroxylgroup, an alcohol for example. Specific examples of these materialsinclude n-tridecyl hexaethylene glycol monoether, isotridecylnonapropylene glycol monoether, n-decyl pcntadecabutoxy alcohol andn-butyl dodecaisopropoxy alcohol. Also included are monoethers ofpolyglycols wherein the polymeric chain may consist of differentalkylene oxide groups, for example ethylene oxide and propylene oxide inthe same chain.

These products made by the condensation of alkylene oxides are mixturesof monoethers of polyglycols of varying chain length. The assignment ofa formula such as in preparing the additives of the present invention isimmaterial so long as the chain lengths lie Within the limits outlinedabove. Monoethers suitable for use in preparing the phosphates fromwhich the additives are made are fully described in US. Patents2,425,755 and 2,425,845.

In preparing the phosphates, equimolar quantifies of the monoether andthe phosphorus pentoxide are mixed and heated at a temperature of fromabout 80 F. to 450 F. for a period of from 0.1 to hours. Nitrogen orother inert gas may be bubbled through the reaction mixture in order toprovide agitation, to prevent oxidation of the reactant material, and toassist in carrying away any water which may be formed. Upon completionof the reaction, the mixture is filtered and the phosphate ester may beseparated from the unreacted material by vacuum distillation or otherprocedures well known in the art. Normally about 50% conversion to themono phosphate is obtained.

The tetra alkyl ammonium salts of the phosphates formed as describedabove are prepared by treating the phosphate with a tetra alkyl ammoniumhydroxide, e.g. tetra ethyl ammonium hydroxide. The hydroxide ispreferably employed in aqueous solution and may he added to thephosphate in the presence of a suitable solvent such as benzene. Thereactants are preferably mixed in equimolar amounts. The reactionmixture is then refluxed at a temperature of from about 140 F. to about212 F. for a period of from about 2 to about 6 hours. Water formed bythe reaction and the water initially present are removed during thereaction and the resulting product is substantially anhydrous, althoughI a slight haze may be present. The product may be filtered to removethis haze and the solvent employed may then be removed by vacuumdistillation to obtain the final product.

The petroleum distillate fuels in which the additive materials of theinvention are employed consist of a major proportion, at least 95%, ofliquid hydrocarbons boiling at temperatures between about 70 F. andabout 750 F. These fuels include gasolines such as aviation,

marine and automotive or motor gasolines, aviation turbo-jet fuels suchas JP-l, JP-4 and JP-S fuels, and diesel fuels such as marine,stationary and automotive diesel engine fuels.

Gasoline consists of at least 95 percent of a mixture of volatilehydrocarbons and may contain various beneficial additives such asantiknock agents, scavenging agents, antioxidants, dyes, anti-icingagents and solvent oils in a total additive concentration not exceeding5 percent by weight.

The volatility of gasoline is such that it has vapor pressures between 5and 15 pounds per square inch at a temperature of 100 F. when determinedin accordance with ASTM Method D 323-56. It has a boiling range between75 F. and 450 F. when determined by ASTM Method D 86-56. Aviationgastion D 439-56 T as falling within three grades and have end pointsnot exceeding 450 F. The viscosity of gasolines is between 0.264 and 1.0centistokes at 100 F.

Aviation turbo-jet fuel consists of at least 95 percent oi a mixture ofvolatile hydrocarbons. It is defined by Military pecificationsMIL-F-5616 and MIL-F- 5624 C. Its volatility is such that its end pointdoes-not exceed 572 F. Its viscosity is between 0.5 and 1.5 centistokesat 100 F.

Diesel fuels as referred to in connection with the inp vention consistof at least 95% of a mixture of hydrocarbons boiling between 250 F. and750 F. either by ASTM Method D 86-56 when their end points do not exceed600 F. or by ASTM Method D 158-54. Diesel fuels are defined by ASTMSpecification D 975-53 T and fall into Grades 1D, 2D and 4D, in allofwhich the additive materials of the invention may be used. They haveviscosities between 1.4 and 26.4 centistokes.

The liquid fuels in which the additive materials may be '4 incorporatedthus comprise at least by weight of a mixture of hydrocarbons having aboiling range between the limits of 75 F. and 750 F. and a viscositybetween the limits of 0.264 and 26.4 centistokes at F.

The additives may be incorporated in such fuels in concentrations offrom about 0.001% by weight to about 0.5% by weight. Concentrations inthe range between about 0.005% to about 0.1% by weight are particularlyeffective.

In order to further illustrate the invention, reference is made to thefollowing examples.

EXAMPLE I N-butyl dodecapropoxy mono-phosphate was prepared by mixing 96wt. per cent of monobutyl dodecapropoxy glycol obtained commerciallywith 4% by wt. of phosphorous pentoxide. The mixture was heated to atemperature of 300 F. and held at that temperature for a period of 4hours. Nitrogen was constantly bubbled through the mixture to provideagitation, prevent oxidation and carry away moisture formed. At the endof the 4 hour period, the reaction mixture was cooled, filtered, and thephosphate formed was recovered. Analysis showed that about 50% of thestarting material was converted to the mono-phosphate and a small amountof the diphosphate and that the product contained 1.7 percent ofphosphorus and had 'a, molecular weight of 889.

The tetra ethyl ammonium salt of the n-butyl dodecapropoxy phosphatethus formed was prepared by mixing 100 grams of the n-butyldodecapropoxy phosphate with 83' grams of a 10% aqueous solution oftetar ethyl ammonium hydroxide in cc. of benzene. The mixture wasrefluxed at a temperature of 176 F. for a period of 4 hours in a sidearm type refluxing apparatus. The product obtained was filtered througha paper filter and'benzene was subsequently removed by vacuumdistillation. Analysis confirmed the formation of the tetra ethylammonium salt of the n-butyl dodecapropoxy phosphate.

EXAMPLE H The additive material produced as described above wasincorporated into examples of a premium quality commercial gasoline andthese samples were subjected to an ASTM Breakdown Test in order to testthe effectiveness of the additive for reducing oxidation of thegasoline.

Typical inspections of the gasoline used are as follows:

' The additive was incorporated in the gasoline in a concentration of0.03% by weight. Measured amounts of the gasoline containing theadditive and the same gasolinewithout the additive were placed in glasscontainers in a bomb. The bomb was filled with pure oxygen at apressurewof 100 psi. and placed in a boiling water bath. The bombpressure gauge was read periodically .andthe test was continued untiloxidation of the fuel causedzthe pressure to drop at a rate of 2 p.s.i.per 15 minute-interval. The time required to-reach this rate is A.S.T.M.breakdown test A.S.T.M, breakdown time, minutes Fuel:

Base gasoline s 260 Base gasoline+0.03 wt. percent of tetraethylammonium salt of n-butyl dodecaproxy phosphate 370 From the above it canbe seen that the time required for oxidation of the fuel wassignificantly increased by the addition of the additive material. Thetest employed is a severe one and it will be appreciated that theimprovement in stability was of considerable magnitude.

EXAMPLE III 6 fined by U.S. Military Specification MIL-E5624 C boilingbetween about 300 F. and 550 F. and samples of the same fuel to whichhad been added 0.01 wt. percent of the tetra ethyl ammonium salt ofu-butyl dodecapropoxy monophosphate were placed in a glass system andpumped at a rate of 1500 cc. per minute through a glass wool plug. Thetime required for a 7.0 kilovolt dis-' charge to be' obtained from acondenser placed in the system was measured. In a second series of teststhe time in seconds to charge a 125 micromicrofarad condenser to 2.5kilovolts when a -'7 .0 kilovolt charge-was applied to the test liquidwas measured. In a third series of tests 80 milliliters of each fuelwere shaken with milliliters of water for 2 minutes and then allowed tosettle for 5 minutes. The amount of water lost in each sample was thendetermined. A jet fuel containing calcium sulfonate, an ionic material,and other materials containing the active groups of the additives of theinvention were also tested. The results of these tests are In order todemonstrate the rust inhibiting properties 0 shown below.

Efiect of additives on static electricity and water tolerance of jetfuels [0.01 Weight percent additive in jet fuel kerosine] Pumping test 1Oqnduc- Water Additive tlvity tolerance 3 test 2 Init. 2 min. 10 min.

None 6 sec. 7 sec 10 sec... 70.0 sec.- O.5 m1. Tetra ethyl ammonium saltof n-butyl dodecapropoxy phosphate 2. 0 O.5.

Calcium sulfonate Reaction product of amine and n-butyl dodecapropoxyphosphate. R%acion (product of polymerized olefin and tetra ethyl ammonm y lOXl e 1 Pumping test: Time in seconds for successive 7.0 kv.discharge at indicated pumping time. Flow rate of 1,500 cc./min. thruglass wool plug.

2 Conductivity test: Time in seconds to charge 125 uni. condenser to 2.5kv. when 7.0 kv. is applied thru test liquid. 3 Water tolerance: Loss ofH20 in ml. when 80 ml. of fuel are shaken with 20 ml. of H20. Shake for2 min., allow to settle for 5 min., read water loss on graduatedcylinder scale.

4 N 0 discharge.

6 Mixture of 0 -02 tertiary alkyl primary amines.

of the additive materials, a commercial gasoline similar to thatemployed in the preceding tests was subjected to a rust test with andwithout the additive. 500 cc. samples of the gasoline and the gasolinecontaining the additive were each mixed with 500 cc. of tap water andpolished steel test panels were immersed in each sample so that half ofeach panel was in the aqueous phase and half was in the upper gasolinephase. Air was bubbled through the liquid at a rate of 500 cc. perminute for one hour. The samples were then sealed and the test panelswere observed periodically for evidence of rusting. It was found thatthe sample containing the tetra ethyl ammonium salt of n butyldodecapropoxy phosphate as an additive material was completely protectedagainst rusting, while severe rusting took place in the samplescontaining no additive. The data obtained in this test are shown below.

Advantages of tetra alkyl ammonium salts of alkylpolyalkyleneoxyphosphates in inhibiting rust Sample Appearance of panel Base gasolineHeavy rust in Shours. Base gasoline 0.03 weight percent of tetra ethylammonium salt of rl-butyl dodecapropoxy phosphate No rust in 75 days.

EXAMPLE IV The effectiveness of the additive materials of the inventionas anti-static agents is shown by pumping tests, conductivity tests andwater tolerance tests carried out upon a turbo-jet aviation fuel withand without the additive. Samples of a turbo-jet fuel of Grade JP-5 asde- The data in the above table clearly demonstrate the superiority ofthe additives of the invention as antistatic agents over similarmaterials. It should be noted that, while calcium sulfonate, also anionic material, reduced static buildup by increasing the conductivity ofthe fuel, this additive was unsatisfactory for use as an anti-staticagent because it increased the solubility of water in the fuel and sofailed to pass the water tolerance test. Similarly, the last two itemsin the table show that the desired properties are not due to the tetraalkyl group or the phosphate group alone but are peculiar to thereaction product containing both groups. Only the tetra ethyl ammoniumsalt of n-butyl dodecapropoxy phosphate, of the materials tested,effectively reduced static build-up without increasing water solubilityin the fuel unduly.

It is believed the data presented in the foregoing examples clearlydemonstrate the efiectiveness of the additive materials of the inventionfor stabilizing petroleum distillate fuels, inhibiting such fuelsagain-st rust and corrosion, and reducing static build-up in such fuels.It will be understood that the additive materials of the invention maybe incorporated into such fuels in conjunction with other additivematerials intended to correct other fuel deficiencies.

What is claimed is:

l. A petroleum distillate fuel boiling in the range between about 75 F.and about 750 F. having incorporated therein from about 0.001% to about0.5% by weight of a tetra alkyl ammonium salt of an alkylpolyalkyleneoxyester of phosphoric acid having the formula where R is an alkyl groupcontaining from 2 to 13 carbon atoms, R is a divalent aliphatichydrocarbon radical having from 2 to 8 carbon atoms, n is from 8 to 1 8,x is an integer from 1 to 2, and R is an alkyl group containing from 1to 4 carbon atoms.

.2. A fuel as defined by claim 1 wherein said ester is an alkylpolypropoxy ester.

3. A fuel as defined by claim 1 wherein said ester is an alkylpolyethoxy ester. y

4. A fuel as defined by claim 1 wherein said salt is a tetra ethylammonium salt.

5. A fuel as defined by claim 1 wherein said ester is n-butyldodecapropoxy phosphate.

6. A petroleum distillate fuel boiling in the range between about 75 F.and about 750 F. having incorporated therein from about 0.001% to about0.5% by weight of a tetra alkyl ammonium salt of n-butyl dodecapropoxyphosphate, the alkyl groups in the tetra alkylammonium radical of saidsalt each containing from 1 to 4 carbon atoms.

7. A fuel as defined by claim 6 wherein said salt is present in a.concentration of from about 0.005% to 10 about 0.1% by weight.

No references cited.

1. A PETROLEUM DISTILLATE FUEL BOILING IN THE RANGE BETWEEN ABOUT 75*F.AND ABOUT 750*F. HAVING INCORPORATED THEREIN FROM ABOUT 0.001% TO ABOUT0.5% BY WEIGHT OF A TETRA ALKYL AMMONIUM SALT OF AN ALKYLPOLYALKYLENEOXYESTER OF PHOSPHORIC ACID HAVING THE FORMULA